Wireless telegraphy.



L DE FOREST.

WIRELESS TELEGRAPHY.

APPLICATION FILED SEPT-24. 1912.

1 141 93, Patented Jan. 30, 1917.

WITNESSES: INVENTOR.

M ATTORNEYS,

'inga spark, frequency, etc.

LEE DE EonEsT, 0E

PAID ALTO, CALIFORNIA, ASSIGNOR TO FEDERAL TELEGRAPH COMPANY, A CORPORATION OF CALIFORNIA.

WIRELESS TELEGRAPHY.

Specification of Letters Patent.

Patented Jan. 3 1), 1917.

Application filed September 24, 1912. Serial No. 722,050.

To all whom it may concern:

Be it known that 1, LEE DE Fonns'r, a citi- -zen of the United States, and a resident of the city of Palo Alto, county of Santa Clara, State of California, have invented new and useful Improvements in Wireless Telegraphy, of which the following is a specification.

This invention relates to improvements in wireless telegraphy, and more particularly to the antenna systems thereof.

Broadly stated the invention consists of the electrical association of a main antenna and an auxiliary antenna,

The object of my invent'on is to increase the capacity of antenna radiatingsystems' and at the same time to diminish their radiation resistance, without entailing costly alterations and extensions such as increasing their height, separation or number of supporting masts or towers, etc.

The drawing is a perspective elevation of a double fan or kite shaped radiating main antenna supported between two masts, and

a conventional horizontal auxiliary antenna electrically associated therewith, and supbetween the two antennae are largely limported by the same masts.

High powered wireless telegraph transmitting systems demand large elevated radiating areas, or conductors, having as great a capacity tenna areas be brought close to the earth large capacity is obtained, but at the sacrifice of radiating qualities, Similarly it is possible to increase the capacity of the oscillating transmitter system merely by connectseparated by a suitable dielectric, in shunt around the inductance and spark gap or arc, at the base of the antenna, as shown at 17. Such a condenser in parallel with the capacity formed between the antenna an earth, while acting as a storage of electric energy to increase the natural period of oscillation of the system, will not materially aid in the radiation of energy of which the system is capable with a given potential, The demand on the initial source'of supply isincreased little if any by the addition of such a condenser 17. i I have found, however, that when an additional capacity of the antenna-earth system is produced in the manner shown, by erecting a second or auxiliary system in suitable proximity to and in electo earth as possible. If these an- I condensermade up of metallic plates originally induced upon the surface elevatedconductor trical relation with the main radiating antenna-a genuine and very marked increase in the energy drawn from the source of supply (s) is obtained and radiated as useful energy.

The main radiating system comprising the antenna 123 is double fan-shaped and is supported by an insulated horizontal cable stretched between the ma'sts M. The conductors of the antenna are connected together at the bottom and the common point of connection is connected to earth 8, through a conductor including the inductance 5v and the are or spark gap 6. The source of power S is connected to the conductor at opposite sides of the oscillation-producer and a-key 7 is arranged in the power circuit. The source of energy supply S in the system here shown is preferably of the direct current type.

By this arrangement, wherein the aum'liary grounded antenna 10-10 is chiefly surrounded or inclosed by the radiating antenna, the tendency of the former to radiate is minimized.

Ihe electro-static lines offorce extending ited to the space within the cage formed by the outer, or main antenna. These force lines are so long that, as the oppositely signed electric charges residing on the 'two antennae. surge, downward to the common ground 8, these interior lines of force loop themselves and radiate outwardly on the earth surface, exactly as do those lines of force which originally extended from the outside of the main antenna to. the neighboring earth.

On account of the relatively-long path a phase displacementbetween these charges and the like signed charges which gvelil'e o t e surrounding earth. This phase difierence represents a loss in the efliciency with which this .new arrangement of earthed auxiliaryantenna" would otherwise operate, and. iftoo great, (i; e., approaching 180) would mean a more or less complete neutralization of the useful radiation from the main antenna. Hence it is desirable to make the paths of the currents from 10-10 to earth 10-11 and 10-12, as short and as near inductionwhich the electric charges originally residing on the small antenna 10'-10 must travel d 7 before reaching earth, there is more or less of high with maximum transverse spread between the two fans of 400 feet, I have found that a flat top; horizontally extending auxiliary antenna 1010,,600 feet long, feet wide, and elevated 200 feet above the earth, will give an increase of thirtythree per cent. of energy drawn from the source of supply, and an increase of thirty to forty per cent. in the high frequency current in the main antenna. The strength of the signals at the distant receiving station is correspondingly increased by this arrangement. 1

Many other modifications and arrangements for carrying out the purpose of my' invention with various types of antenna systems, v guys, etc., will at once suggest themselves to those skilled in the art.

What I claim and wish to protect by Letters Patent is: v

1. In a transmission system for wireless communication, an elevated fan shaped main antenna, a conductor connecting said supplementary antenna to earth.

2. In a transmission system for wireless communication, .an elevated fan-shaped main antenna, a conductor connecting said antenna to earth, an inductance and a source of electrical oscillations inseries in said conductor, a capacity in shunt on said inductance and source of oscillations, a supplementary horizontal antenna arranged within and insulated from said main antenna and a conductor connecting said supplementary antenna directly to earth.

In testimony whereof, I have hereunto set my hand at San Francisco, California, this 16th day of September, 1912.

LEE DE FOREST.

In presence of- BALDWIN VALE, P. S. PEWELL."

. ranged within and insulated from said main I antenna and a conductor connecting said 

